Optical pickup actuator

ABSTRACT

There is provided an optical pickup actuator for actuating a lens holder having an object lens according to an interaction between coils and magnets. The optical pickup actuator includes a lens-seating portion formed on the lens holder to support the object lens and a lens guide portion protruding from the lens-seating portion to securely support the object lens. The lens guide portion has an adhesive confining groove in which adhesive can be injected to securely fix the object lens.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical pickup actuator for reading and writing data from and to an optical recording medium.

2. Description of the Related Art

The optical pickup actuator maintains a relative location between an object lens and an optical recording medium at a predetermined distance by moving a moving part on which the object lens is mounted and reads and writes information from and to the optical recording medium by following a track of the optical recording medium.

The optical pickup actuator has a permanent magnet and a coil. When the electric current is applied to the coil, the optical pickup actuator moves the object lens to a desired location. At this point, the moving part moves in focusing and tracking directions that are perpendicular to each other.

FIGS. 1A and 1B are schematic views of an optical pickup actuator according to the related art.

Referring to FIGS. 1A and 1B, an optical pickup actuator includes a lens holder 102 for mounting an object lens on a central portion thereof and having an outer circumference around which tracking and focusing coils 106 and 105 are wound, magnets and yokes 103 and 104 installed on the base and opposing the tracking and focusing coils 106 and 105 of the lens holder 102, a plurality of wire suspensions 107 each having a first end fixed on a side surface of the lens holder to support the lens holder 102, and a damper holder 109 to which a second end of each wire suspensions 107 is fixed.

Reference numeral 109 denotes fixing plates fixed on the lens holder 102 and the first ends of the wire suspensions 107 are fixed on the fixing plates 109 through a soldering process.

The optical pickup actuator will be now described in more detail.

The object lens 101 is mounted on the central portion of the lens holder 102. The focusing coil 105 for focusing is wound around each corner of the lens holder. The tracking coil for tracking is wound around a center portion of left and right surfaces of the lens holder 102.

The yokes 104 are formed of a ferromagnetism material protrude. The yokes face the focusing and tracking coils 105 and 106. The magnets are fixed on front surfaces of the respective yokes 104. The yokes 104 are fixed on a pickup base (not shown).

The fixing plates 108 are couple to the lens holder 102. The first ends of a pair of wire suspensions 107 parallel to each other are fixed to each fixing plate 108 through the soldering process. The second ends of the wire suspensions are fixedly inserted in a damper of the damper holder 109.

The damper is coupled inside the damper holder 109 so that the wire suspensions each having a rigidity can has a damping property. A main board (not shown) is coupled to an outer surface of the damper holder 109. The second ends of the wire suspensions 107 are actually fixed on the main board.

The lens holder 102 is lifted by the wire suspensions 107 and electric current is applied to the wire suspensions 107.

When electric current is applied to the tracking coil 106, repulsive and attractive forces are generated by an electromagnetic force between the focusing coil 105 and the magnets 103. By the repulsive and attractive forces, the lens holder 102 moves in the focusing direction (in a vertical direction), thereby operating a focusing servo for compensating for a focusing error.

The above-described optical pickup actuator is a moving coil type where the focusing and tracking coils 105 and 106 move together with the lens holder 102 around which the focusing and tracking coils 105 and 16 are wound.

There is also a moving magnet type where the magnets are attached on the outer circumference of the lens holder so as to move together with the lens holder. At this point, the movement using the magnets and the coils uses Lorentz's force of Fleming's left-hand rule.

The above-described optical pickup actuator reads and writes information on an optical recording medium. In recent years, as multimedia systems have been rapidly developed and capacities of multimedia contents such as games and movies has been increased, it has been required that the optical pickup actuator must be reliable to stably drive the multimedia systems for many hours.

When the multimedia system is driven for many hours, heat is generated by the electric current applied to the coils of the optical pickup actuator and transmitted to the object lens through the lens holder.

When the heat generated by the coils is transmitted to the object lens for a long time, the aberration is increased. Furthermore, when excessive electric current is applied to the coils, the object lens may be cracked due to a thermal-stress. Therefore, there is a need for an optical pickup actuator that can improve a driving reliability by reducing the heat transmitted from the coils to the object lens.

Also, in a high speed optical pickup actuator, even when the object lens is attached to the lens holder using adhesive, the lens holder may be different in a frequency response from the object lens since the adhesive force is not enough. That is, a resonance peak of the lens holder may be greater than a resonance peak of the object lens.

Therefore, there is also a need for an optical pickup actuator that can improve the driving reliability by attenuating the resonance characteristics.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an optical lens actuator that substantially obviates one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide an optical pickup actuator that can minimize the transmission of heat from coils to an object lens by forming recessed portions on side surfaces of a lens holder.

Another object of the present invention is to provide an optical pickup actuator that can block out heat that is transmitted from coils to an object lens by processing heat discharge grooves on a lens-seating portion surrounding a beam-passing hole.

Still another object of the present invention is to provide an optical pickup actuator that can enhance a bonding force of an object lens by improving a bonding structure between a lens holder and the object lens.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided an optical pickup actuator for actuating a lens holder having an object lens according to an interaction between coils and magnets, the optical pickup actuator including: a lens-seating portion formed on the lens holder to support the object lens; and a lens guide portion protruding from the lens-seating portion to securely support the object lens, wherein the lens guide portion has an adhesive confining groove in which adhesive can be injected to securely fix the object lens.

In another aspect of the present invention, there is provided an optical pickup actuator for actuating a lens holder having an object lens according to an interaction between coils and magnets, the optical pickup actuator, wherein the lens holder is provided at a side surface with a dissipation groove that does not directly contact a tracking coil.

In still another aspect of the present invention, there is provided an optical pickup actuator comprising: a lens holder having a lens-seating portion on which an object lens seats and a bobbin around which a focusing coil is wound, and a coil-supporting portion around which a tracking coil is wound, wherein the coil-supporting portion protrudes from a side surface of the lens holder and the side surface of the lens holder is provided with a coil-contacting portion contacting the tracking coil and a heat dissipation groove that does not contact the tracking coil.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:

FIGS. 1A and 1B are schematic views of an optical pickup actuator according to the related art; and

FIGS. 2 through 4 are views illustrating an optical pickup actuator according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

FIGS. 2 through 4 are views illustrating an optical pickup actuator according to an embodiment of the present invention.

Referring to FIGS. 2 through 4, a lens holder 202 has first heat dissipation grooves 204 formed on a lens-seating portion 209 on which an object lens 201 seats, second heat dissipation grooves 225 formed on centers of opposite side surfaces of the lens holder 202, and third heat dissipation grooves 232 formed on left and right portions of each of the opposite side surfaces of the lens holder 202.

The object lens 201 seating on the lens-seating portion 209 is aligned with a beam-passing hole 203 surrounded by the lens-seating portion 209. Lens guide portions 211 protrude from the lens-seating portion 209 to fixedly support the object lens 201. The lens guide portions 211 are formed along a circumference having an inner diameter greater than an outer diameter of the object lens 201.

The lens guide portions 211 are opened upward and toward a location where the object lens is located. For example, the lens guide portions 211 may be disposed about 90° apart. Each of the lens guide portion 211 has an adhesive confining groove 212 and an adhesive reinforcing projection 213 for dividing the adhesive confining groove 212 into two sections. The adhesive reinforcing projection 213 extends toward the object lens.

One or more reinforcing projections 213 may be formed on each lens guide portion 211, having a height lower than that of the lens guide portion 211.

Referring to FIG. 4, the adhesive is injected into the lens guide portion 211 after the object lens 201 seats on the lens-seating portion 209. The adhesive may be a UV adhesive or a bond. The injected adhesive does not leak out of the lens guide portion 211 due to the internal structure of the lens guide portion 211. At this point, since the adhesive reinforcing projection 213 is formed in the adhesive confining groove 212, the adhesive force of the adhesive can be more enhanced.

As the adhesive is applied between he lens guide portions 211 and the object lens 201, the adhesive force for bonding the object lens 201 to the lens holder 202 is further enhanced.

Accordingly, when the lens holder 202 is driven at a high speed, the resonance peak of the object lens 201 becomes identical to that of the lens holder 202.

Meanwhile, the first heat dissipation grooves 204 are respectively formed on opposite portion of the lens-seating portion 209 that are adjacent to the coils. By the first heat dissipation grooves 204, portions of the object lens 201 do not contact the lens-seating portion 209.

Therefore, an amount of the heat transmitted to the object lens 201 through the lens-seating portion 209 can be reduced.

Also, second heat dissipation means is formed on the centers of the opposite surfaces of the lens holder 200. The second heat dissipation means includes second coil contacting portions 223 and 224 on which portions where coil-supporting portions 221 and 222 will be formed are elevated so that upper and lower portions of the tracking coils 206 contact the coil supporting portions 221. The second heat dissipation means further includes the second dissipation grooves 225 formed portions where a middle portion of an inner surface of the tracking coil 206 will contact. By the second dissipation grooves 225, portions of the tracking coil 206 do not contact the lens holder 202.

Here, each of the second heat dissipation grooves 225 may be unevenly formed and has a width wider than those of the second coil contacting portions 223 and 224.

Also, third heat dissipation means is formed by stepping left and right sides of opposite surface of the lens holder 202, which corresponds to inner surfaces of bobbins 230 around which the focusing coil 205 is wound. The third heat dissipation means includes third contacting portions 231 to which upper and lower portions of the focusing coil 205 contact. The third contacting portions 231 are elevated from the opposing surfaces of the lens holder 202. The third heat dissipation means further includes third heat dissipation grooves 232 formed on the opposite surface of the lens holder 202. The third heat dissipation grooves 232 correspond to the middle portion of the focusing coil 205. Therefore, the middle portion of the focusing coil does not directly contact the lens holder 202 by the third dissipation grooves 232.

Each of the third heat dissipation grooves 225 may be unevenly formed and has a width defined between the upper and lower bobbins 230. Preferably, the width of the third heat dissipation grooves 225 is wider than those of the third coil contacting portions 231.

The case where the coils are wound around the lens holder 202 having the above described first and second heat dissipation means is illustrated in FIG. 3.

The coils may be formed in a variety of shapes such as a rectangular shape or a trapezoid shape.

Referring to FIG. 3, the tracking coils 206 are wound around middle portions of the opposite surfaces of the lens holder 202 and the focusing and radial coils 205 and 207 are wound around left and right sides of the opposite surfaces of the lens holder 202. The tracking coils 206 are supported by the coil supporting portions 221 and 222 and the middle portion of the inner surfaces of the tracking coils 206 are spaced away from the opposite surfaces of the lens holder 202 by the second heat dissipation grooves 225. That is, since the upper and lower portions of the inner surfaces of the tracking coils 206 contact the second coil contacting portions 223 and 224, the middle portions of the inner surfaces of the tracking coils 206 do not directly contact the lens holder 202 by the second dissipation grooves 225. Accordingly, an amount of the heat generated by the tracking coils 206 and transmitted to the object lens can be reduced.

Furthermore, the focusing and radial coils 205 and 207 are dually wound. Middle portions of the inner surfaces of the focusing and radial coils 205 and 207 do not directly contact the tracking coil 206 by the third heat dissipation grooves 232 stepped inward from the third coil contacting portions 131. Therefore, an amount of heat generated from the focusing and radial coils 205 and 207 and transmitted to the object lens can be reduced.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 

1. An optical pickup actuator for actuating a lens holder having an object lens according to an interaction between coils and magnets, the optical pickup actuator comprising; a lens-seating portion formed on the lens holder to support the object lens; and a lens guide portion protruding from the lens-seating portion to securely support the object lens, wherein the lens-seating portion has a heat dissipation groove that does not directly contact the object lens.
 2. The optical pickup actuator according to claim 1, wherein the lens guide portion has an adhesive confining groove in which adhesive can be injected to securely fix the object lens.
 3. The optical pickup actuator according to claim 1, wherein the lens guide portion is opened upward and toward the object lens so that the adhesive can be injected in a space defined between an inner surface of the lens guide portion and the object lens.
 4. The optical pickup actuator according to claim 2, wherein the lens guide portion has an adhesive reinforcing projection dividing the adhesive confining groove into two sections.
 5. The optical pickup actuator according to claim 1, further comprising one or more additional lens guide portions.
 6. An optical pickup actuator for actuating a lens holder having an object lens according to an interaction between coils and magnets, the optical pickup actuator, wherein the lens holder is provided at a side surface with a dissipation groove that does not directly contact a tracking coil, wherein the lens holder has a lens-seating portion having a heat dissipation groove that does not directly contact the object lens.
 7. The optical pickup actuator according to claim 6, wherein the lens holder is further provided at the side surface with a heat dissipation groove that does not directly contact a focusing coil.
 8. The optical pickup actuator according to claim 6, wherein the lens holder is further provided at the side surface with a heat dissipation groove that does not directly contact a radial coil.
 9. An optical pickup actuator comprising: a lens holder having a lens-seating portion on which an object lens seats and a bobbin around which a focusing coil is wound, and a coil-supporting portion around which a tracking coil is wound, wherein the coil-supporting portion protrudes from a side surface of the lens holder and the side surface of the lens holder is provided with a coil-contacting portion contacting the tracking coil and a heat dissipation groove that does not contact the tracking coil, and wherein the lens-seating portion has a heat dissipation aroove that does not directly contact the object lens.
 10. The optical pickup actuator according to claim 9, wherein the bobbin protrudes from the side surface of the lens holder and the side surface is further provided with a coil contacting portion contacting the focusing coil and a dissipation groove that does not contact the focusing coil.
 11. The optical pickup actuator according to claim 10, further comprising a radial coil wound around the bobbin.
 12. The optical pickup actuator according to claim 9, further comprising a lens guide portion formed on the lens-seating portion to support the object lens and an adhesive confining groove for confining adhesive for securely fix the object lens to the lens guide portion.
 13. The optical pickup actuator according to claim 12, wherein the lens guide portion includes an adhesive reinforcing protrusions for dividing the adhesive confining groove into two sections.
 14. The optical pickup actuator according to claim 12, wherein the lens guide portion is opened upward and toward the object lens so that the adhesive can be injected in a space defined between an inner surface of the lens guide portion and the object lens.
 15. The optical pickup actuator according to claim 12, further comprising one or more additional lens guide portions.
 16. An optical pickup actuator for actuating a lens holder having an object lens according to an interaction between coils and magnets, the optical pickup actuator comprising; a lens-seating portion formed on the lens holder to support the object lens; and a lens guide portion protruding from the lens-seating portion to securely support the object lens, wherein the lens guide portion has an adhesive confining groove in which adhesive can be injected to securely fix the object lens and an adhesive reinforcing projection dividing the adhesive confining groove into two sections.
 17. The optical pickup actuator according to claim 16, wherein the lens guide portion is opened upward and toward the object lens so that the adhesive can be injected in a space defined between an inner surface of the lens guide portion and the object lens.
 18. The optical pickup actuator according to claim 16, further comprising one or more additional lens guide portions. 